Display device

ABSTRACT

A display device is disclosed, which comprises: a substrate; a first metal conductive layer disposed on the substrate; a semiconductor layer disposed on the first metal conductive layer and having a top surface; and a second metal conductive layer disposed on the top surface and comprising a first part and a second part. Herein, a first extending direction is defined as a direction that the first part extends toward the second part, the first part has a maximum length in a first region that the first part overlaps the first metal conductive layer along the first extending direction, the first part has a maximum width in a second region that the first part overlaps the semiconductor layer along a second direction vertical to the first extending direction, and the maximum length is greater than the maximum width and less than or equal to twice of the maximum width.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefits of the Chinese Patent ApplicationSerial Number 201510744136.8, filed on Nov. 5, 2015, the subject matterof which is incorporated herein by reference.

BACKGROUND

1. Field of the Disclosure

The present disclosure relates to a display device and, moreparticularly, to a display device in which a source or drain electrodehas specific width or length to ensure a switch performance of a thinfilm transistor structure and a display quality of the display device.

2. Description of Related Art

In recent years, all the display devices are developed toward havingsmall volume, thin thickness or light weight as the display techniquesprogresses. Hence, a conventional cathode ray tube (CRT) display isgradually replaced by a liquid crystal display (LCD) device, an organiclight emitting diode (OLED) display device or the like. In addition,with the development of flexible substrates, the LCD device and the OLEDdisplay device are not limited to conventional display devices, but alsocan be flexible display devices equipped with flexible substrates. Theconventional or flexible LCD device or the conventional or flexible OLEDdisplay devices can be applied to various fields. For example, the dailyused devices such as cell phones, notebooks, video cameras, cameras,music players, navigation devices, and televisions are equipped withthese display devices.

Although the LCD devices and OLED display devices are commerciallyavailable, and especially the techniques for the LCD devices are wellmatured, every manufacturer is desired to develop display devices withimproved display quality to meet customers' requirement for high displayquality as the display devices developed. For the conventional displaydevices or the flexible display devices, the structure of the thin filmtransistors on the display region is one factor related to the overallefficiency of the display device.

Therefore, it is desirable to provide an improved thin film transistorstructure on the display region to further enhance the display qualityof the display device.

SUMMARY

An object of the present disclosure is to provide a display device,wherein a first part of the second metal conductive layer as a source ordrain electrode has a specific width or length, to ensure the switchperformances of the thin film transistor structure or assure the opticalproperty of the display device.

Hereinafter, the first part can be a source or drain electrode; if thefirst part is defined as a source electrode, the second part is definedas a drain electrode; and vice versa.

The display device of the present disclosure comprises: a substrate; afirst metal conductive layer disposed on the substrate; a semiconductorlayer disposed on the first metal conductive layer and having a topsurface; and a second metal conductive layer disposed on the topsurface, wherein the second metal conductive layer comprises a firstpart and a second part, the first part extends toward the second part,the first part is apart from the second part in a distance and forms achannel region with the semiconductor layer, and the second metalconductive layer, the first metal conductive layer and the semiconductorlayer forms a thin film transistor structure. Herein, a first extendingdirection is defined as a direction that the first part extends towardthe second part, a second direction is defined as a direction verticalto the first extending direction, a first region is defined as a regionthat the first part overlaps the first metal conductive layer, a secondregion is defined as a region that the first part overlaps thesemiconductor layer, the first part has a maximum length (b) in thefirst region along the first extending direction, the first part has amaximum width (a) in the second region along the second direction, andthe maximum length is greater than the maximum width and less than orequal to twice of the maximum width (a<b≦2a).

Hence, in the display device of the present disclosure, the first partof the second metal conductive layer as a source electrode is designedto have a specific width or length. When the first part has the specificwidth or length, the area of the second region between the first partand the semiconductor layer can be ensured, and the total length of theedges of the first part in this second region can also be kept.Therefore, the switch performance of the TFT structure or the opticalproperty of the display device can be assured.

Other objects, advantages, and novel features of the disclosure willbecome more apparent from the following detailed description when takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a display device according anembodiment of the present disclosure;

FIGS. 2A and 2B are top views of a TFT structure according to anembodiment of the present disclosure;

FIG. 3 is a cross-sectional view of a TFT structure according to anembodiment of the present disclosure;

FIG. 4 is a diagram showing a relation of a resistance and a feedthroughvoltage vs. an area of a second region of a first part and asemiconductor layer in a TFT structure according to an embodiment of thepresent disclosure;

FIG. 5 is a perspective view showing components on a substrate of adisplay device according to an embodiment of the present disclosure;

FIG. 6 is a cross-sectional view of a display device according to anembodiment of the present disclosure;

FIGS. 7A and 7B are top views showing a TFT structure and a transparentconductive layer disposed thereon according to an embodiment of thepresent disclosure;

FIG. 8 is a diagram showing a relation of transmittance and contrast vs.a distance between a slit edge of a transparent conductive layer and asecond edge of a first part in a display device according an embodimentof the present disclosure; and

FIG. 9 is a top view of a TFT structure according to another embodimentof the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENT

The present disclosure has been described in an illustrative manner, andit is to be understood that the terminology used is intended to be inthe nature of description rather than of limitation. Many modificationsand variations of the present disclosure are possible in light of theabove teachings. Therefore, it is to be understood that within the scopeof the appended claims, the disclosure may be practiced otherwise thanas specifically described.

Furthermore, the ordinal numbers such as “first” and “second” used inthe present specification and the appended claims are used to modify theunits in the appended claims. The ordinal numbers themselves do not meanor represent the claimed units having ordinal numbers, and do notrepresent the order of one claimed unit to another claimed unit or thesequence of the manufacturing process. The ordinal numbers are used onlyfor naming one claimed unit to clearly distinguish the claimed unit fromthe other claimed unit having the same term.

FIG. 1 is a cross-sectional view of a display device according anembodiment of the present disclosure. The display device of the presentembodiment comprises: a substrate 11; a counter substrate 2 opposite tothe substrate 11; and a display medium layer 3 disposed between thesubstrate 11 and the counter substrate 2. In the present embodiment, thesubstrate 11 can be a TFT substrate with TFT structures (not shown inthe figure) disposed thereon, and the counter substrate 2 can be a colorfilter substrate with a color filter layer (not shown in the figure)disposed thereon. However, in other embodiment of the presentdisclosure, the color filter layer (not shown in the figure) can also bedisposed on the substrate 11; and in this case, the substrate 11 is acolor filter on array (COA) substrate. In addition, the display mediumlayer 3 in the display device of the present embodiment can be a liquidcrystal layer, an organic light emitting diode layer, a light emittingdiode layer, or a quantum dot layer. When the display medium layer 3 inthe display device of the present embodiment is a liquid crystal layer,the display device of the present embodiment may further comprise abacklight module disposed below the substrate 11. Hereinafter, thestructure of the TFT structure on the substrate 11 is described indetail.

In the present embodiment and other embodiments of the presentdisclosure, the display device may be not equipped with the countersubstrate 2. In addition, the substrate 11 can comprise a flexiblesubstrate, and the material of the flexible substrate can be plastic orother material capable of forming the flexible substrate.

FIGS. 2A to 3 are respectively top views and a cross-sectional view of aTFT structure according to an embodiment of the present disclosure,wherein FIG. 3 is a cross-sectional view of FIGS. 2A and 2B along asection line A-A′. FIGS. 2A and 2B are the same top views except thatthe filling patterns are different. The display device of the presentembodiment comprises: a substrate 11; a first metal conductive layer 12disposed on the substrate 11; an insulating layer 13 disposed on thefirst metal conductive layer 12; a semiconductor layer 14 disposed onthe insulating layer 13 and the first metal conductive layer 12 andhaving a top surface 141; and a second metal conductive layer disposedon the top surface 141 and configured a TFT structure with the firstmetal conductive layer 12 and the semiconductor layer 14, wherein thesecond metal conductive layer comprises a first part 151 and a secondpart 152, the first part 151 extends toward the second part 152, and thefirst part 151 is apart from the second part 152 in a distance and formsa channel region 153 with the semiconductor layer 14. Herein, thechannel region 153 is located in the semiconductor layer 14.

In the present embodiment, the substrate 11 can comprise any substratematerial such as glass, plastic or other flexible material; but thepresent disclosure is not limited thereto. The insulating layer 13 cancomprise any insulating material such as oxides, nitrides, ornitroxides; in the present embodiment, the material of the insulatinglayer 13 is silicon nitride (SiNx). The first metal conductive layer 12and the second metal conductive layer (including the first part 151 andthe second part 152) can comprise any conductive material, such asmetals, alloys, metal oxides, metal nitroxides or other electrodematerial. In addition, the semiconductor layer 14 can comprise anysemiconductor material, such as amorphous silicon, polysilicon, metaloxides (for example, IGZO and ZnO); in the present embodiment, thematerial of the semiconductor layer 14 is amorphous silicon (a-Si), andfurther doped with high concentration of P (with PH₃) to form N⁺ a-Si atthe top surface 141. However, in other embodiment of the presentdisclosure, the materials for the aforementioned components are notlimited to the above listed examples.

In addition, in the present embodiment, the first metal conductive layer12 is used as a gate electrode, the insulating layer 13 is used as agate insulating layer, the first part 151 of the second metal conductivelayer is used as a source electrode and the second part 152 thereof isused as a drain electrode. In the present disclosure, the first part 151can be a source or drain electrode; if the first part 151 is defined asa source electrode, the second part 152 is defined as a drain electrode;and vice versa.

For the purpose that the TFT substrate has good switch performance andthe display device has good optical property, the first part 151 of thesecond metal conductive layer in the display device of the presentembodiment has special width or length.

As shown in FIGS. 2A and 2B, herein, a first extending direction De1 isdefined as a direction that the first part 151 extends toward the secondpart 152 is defined as a first extending direction De1, as indicated bythe arrow located on the first part 151; and the second direction De2 isdefined as a direction vertical to the first extending direction De2. Inaddition, a first region R1 is defined as a region that the first part151 overlaps the first metal conductive layer 12, and a second region R2is defined as a region that the first part 151 overlaps thesemiconductor layer 14. The first metal conductive layer 12 has a firstedge 12 a in the first region R1 that the first metal conductive layer12 overlaps the first part 151, the semiconductor layer 14 has asemiconductor layer edge 14 a in the second region R2 that thesemiconductor layer 14 overlaps the first part 151; wherein the firstextending direction De1 is defined as a connection line of a firstcentral point P1 of the first edge 12 a and a second central point P2 ofthe semiconductor layer edge 14 a, as indicated by the arrow located onthe first part 151.

As shown in FIGS. 2A and 2B, the first part 151 has a maximum length (b)in the first region R1 that the first part 151 overlaps the first metalconductive layer 12 along the first extending direction De1, the firstpart 151 has a maximum width (a) in the second region R2 that the firstpart 151 overlaps the semiconductor layer 14 along the second directionDe2 vertical to the first extending direction De1, and the maximumlength (b) is greater than the maximum width (a) and less than or equalto twice of the maximum width (a), i.e. a<b≦2a.

As shown in FIGS. 2A and 2B, when providing a voltage to the displaydevice, the resistance of the first part 151 will influence the currentpassing through the channel region 153 (as shown in FIG. 3). Hence, inorder to maintain enough current, the resistance of the first part 151has to be reduced. In addition, the resistance of the first part 151 isinversely proportional to the area of the first part 151. As the area ofthe first part 151 increased, the resistance thereof is decreased; andas the area of the first part 151 decreased, the resistance thereof isincreased. Furthermore, in order to ensure the current charge capacityof the TFT structure, the contact area between the first part 151 andthe top surface 141 of the semiconductor layer 14 has to be largeenough, and the total length of the edge of the first part 151 in thesecond region R2 that the first part 151 overlaps the semiconductorlayer 14 (i.e. in FIGS. 2A and 2B, the total length of the edge of thefirst part 151 from the point P3 to the point P4 along the outline ofthe first part 151 near to the edge of the second part 15) has to belong enough. Therefore, based on the minimum current that can betolerant to the TFT designs, i.e. based on the maximum resistance thatcan be tolerant, the minimum area of the second region R2 that firstpart 151 overlaps the semiconductor layer 14 has to satisfy thefollowing equation (1):

A=(a/2)²×π=(π/4)×a ²≈0.785a ²  (1)

wherein, “A” is the area of the second region R2 that the first part 151overlaps the semiconductor layer 14; “a” is the maximum width of thefirst part 151 in the second region R2 that the first part 151 overlapsthe semiconductor layer 14 along a second direction De2 vertical to thefirst extending direction De1; and “π” is ratio of the circumference ofa circle to its diameter.

However, the parasitic capacitance generated between the first part 151and the first metal conductive layer 12 may influence the feedthroughvoltage. If the feedthrough voltage is too large, image sticking orflicker may be occurred, resulting in the display quality decreased.Hence, the overlapping area of the first region R1 between the firstpart 151 and the first metal conductive layer 12 cannot be too large, tomaintain the display quality of the display device.

Generally, in the liquid crystal display device, the relation betweenthe feedthrough voltage and the parasitic capacitance is presented bythe following equation (2):

ΔV=(V _(gh) −V _(gl))×C _(gs)/(C _(gs) +C _(lc))  (2)

wherein, “ΔV” is the feedthrough voltage; “V_(gh)” is gate high voltage;“V_(gl)” is gate low voltage; “C_(lc)” is the capacitance of the liquidcrystal layer; and “C_(gs)” is the parasitic capacitance occurred in thefirst region R1 between the first part 151 and the first metalconductive layer 12. As shown in the equation (2), the feedthroughvoltage is increased as the parasitic capacitance increased. Inaddition, when the overlapping area of the first region R1 between thefirst part 151 and the first metal conductive layer 12 is increased, theparasitic capacitance occurred therebetween is also increased. Hence,the overlapping area of the first region R1 between the first part 151and the first metal conductive layer 12 is proportional to thefeedthrough voltage. Therefore, to obtain a permitted feedthroughvoltage, it is necessary to have a maximum overlapping area between thefirst part 151 and the first metal conductive layer 12.

More specifically, in the case that the minimum area of the secondregion R2 that first part 151 overlaps the semiconductor layer 14satisfy the equation (1), the obtained feedthrough voltage is defined as1 times of feedthrough voltage. In general, the feedthrough voltagevariation between 1 to 3 times of feedthrough voltage is acceptable,because the optical quality of the display device can be maintained. Inorder to maintain the feedthough voltage variation within 3 times of thefeedthrough voltage, the maximum area of the first region R1 between thefirst part 151 and the first metal conductive layer 12 has to satisfythe following equation (3):

A1=(2a)×a=2×a ²  (3)

wherein, “A1” is the area of the first region R1 between the first part151 and the first metal conductive layer 12; “a” is the maximum width ofthe first part 151 in a second region R2 that the first part 151overlaps the semiconductor layer 14 along a second direction De2vertical to the first extending direction De1.

FIG. 4 is a diagram showing the relation of the resistance and thefeedthrough voltage vs. the area of the second region R2 of the firstpart 151 and the semiconductor layer 14 in the TFT structure of thepresent embodiment. As shown in FIG. 4, the resistance of the first part151 is inversely proportional to the area of the first part 151. As thearea of the first part 151 increased, the resistance thereof isdecreased; and as the area of the first part 151 decreased, theresistance thereof is increased. In addition, the area of the firstregion R1 between the first part 151 and the first metal conductivelayer 12 is proportional to the feedthrough voltage. As the overlappingarea therebetween increased, the feedthrough voltage is increased; andas the overlapping area therebetween decreased, the feedthrough voltageis decreased. In order to provide enough current and prevent thefeedthrough voltage too large at the same time, the area of the secondregion R2 between the first part 151 and the semiconductor layer 14 hasto simultaneously satisfy the minimum area defined in the equation (1)and the maximum area defined in the equation (2). When the area of thesecond region R2 between the first part 151 and the semiconductor layer14 simultaneously satisfy the minimum area defined in the equation (1)and the maximum area defined in the equation (2), a maximum resistanceR_max and a maximum feedthrough voltage ΔV_max can be obtained.

In the present embodiment, as shown in FIG. 2, the maximum width of thefirst part 151 in a second region R2 that the first part 151 overlapsthe semiconductor layer 14 along a second direction De2 vertical to thefirst extending direction De1 is between 1 μm to 10 μm; or between 2 μmto 6 μm. In addition, the area of the second region R2 that the firstpart 151 overlaps the semiconductor layer 14 is between 0.78 μm² to 200μm²; or between 3.14 μm² to 72 μm². Furthermore, the length of the edgeof the first part 151 in the second region R2 that the first part 151overlaps the semiconductor layer 14 is between 1.57 μm to 15.70 μm; orbetween 3.14 μm to 9.42 μm.

It should be noted that FIG. 4 is a perspective view showing therelation of the resistance and the feedthrough voltage vs. the area ofthe second region R2 of the first part 151 and the semiconductor layer14, which is used to explain the situation that the resistance isdecreased and the feedthrough voltage is increased as the area of thesecond region R2 is increased. However, in fact, the relation of theresistance and the feedthrough voltage vs. the area of the second regionR2 is not certainly identical to the linear relation shown in FIG. 4.

Besides, in an embodiment of the present disclosure, the first part 151and the transparent conductive layer also have designed structures. FIG.5 is a perspective view showing components on the substrate of thedisplay device of the present embodiment; and FIG. 6 is across-sectional view of the display device along the section line B-B′shown in FIG. 5. As shown in FIGS. 5 and 6, the display device of thepresent embodiment further comprises a transparent conductive layer 42,the second metal conductive layer (including the first part 151 and thesecond part 152) further comprises a data line 161, and the data line161 electrically connects to the second part 152. In the presentembodiment, the display device further comprises another transparentconductive layer 41 disposed below the transparent conductive layer 42.Herein, one of the transparent conductive layers 41, 42 is used as acommon electrode layer and the other is used as a pixel electrode layer.In the present embodiment, the transparent conductive layer 41 is usedas a pixel electrode layer and the transparent conductive layer 42 isused as a common electrode layer. Furthermore, the display device of thepresent embodiment further comprises a black matrix layer 21 disposed onthe counter substrate 2 and overlapping with the data line 161. In otherembodiment of the present disclosure, the black matrix layer may bedisposed on the substrate 11; in this case, the substrate 11 is a BOA(black matrix on array) substrate.

Herein, the structure relation between the first part 151 and thetransparent conductive layer 42 in the display device of the presentembodiment is illustrated in detail. FIGS. 7A and 7B are top viewsshowing the TFT structure and the transparent conductive layer disposedthereon; wherein FIGS. 7A and 7B are the same top view except thefilling patterns are different. As shown in FIGS. 5 to 7B, thetransparent conductive layer 42 is disposed above the second metalconductive layer and substantially parallel to the data line 161. Morespecifically, the transparent conductive layer 42 comprises plural stripelectrodes 422 and plural slits 421 alternately arranged, and the slits421 substantially parallel to the data lines 161. Herein, the term“substantially parallel” refers to an angle included between thelongitude extending directions of the slits 421 and the data line 161 is0 to ±5 degree.

As shown in FIGS. 6 and 7A, in the display device of the presentembodiment, there is an overlapping region between the second metalconductive layer and the transparent conductive layer 42. Morespecifically, the second metal conductive layer partially overlaps withat least one of the slits 421. Herein, the region that the second metalconductive layer overlapping the at least one of the slits 421 has awidth W, which is more than 0 and less than 8 μm. More specifically, thefirst part 151 of the second metal conductive layer has a shieldingregion S overlapping the at least one of the slits 421; wherein, in theshielding region S, the slit 421 has a slit edge 421 a, the first part151 has a second edge 151 a, and a distance (i.e. the width W) betweenthe slit edge 421 a and the second edge 151 a is more than 0 and lessthan 8 μm. Herein, the distance (i.e. the width W) between the slit edge421 a and the second edge 151 a is observed at a normal direction of thesubstrate 11, as shown in FIGS. 6 and 7A.

FIG. 8 is a diagram showing a relation of transmittance (T %) andcontrast (CR) vs. the distance (i.e. the width W) between the slit edge421 a of the transparent conductive layer 42 and the second edge 151 aof the first part 151 in the display device of the present embodiment.Herein, the transmittance and contrast detected in a condition that thewidth W is 0 μm in the pixel is set to be 100%, and the transmittanceand contrast change when the width W is increased from 0 μm to 12 μm isexamined. As shown in FIG. 8, as the width W increased, thetransmittance is decreased but the contrast is increased. However, thecontrast is not significant improved but the transmittance is stillgradually decreased, when the width W is more than 8 μm. Hence, in thepresent embodiment, the distance (i.e. the width W) between the slitedge 421 a and the second edge 151 a is more than or equal to 0 μm andless than 8 μm (0 μm≦W<8 μm).

As shown in FIGS. 7A and 8, the liquid crystal molecules may notproperly tilt at the region above the slits 421, resulting in dark linesoccurred. If there is a shielding region S between the first part 151 ofthe second metal conductive layer and the at least one of the slits 421,this shielding region S can cover the region that the dark lines areeasily occurred; and therefore, the contrast at this region can beimproved. Even though the transmittance at this shielding region S isdecreased, the decreased level of the transmittance at this shieldingregion S is very small. However, if the area of the shielding region Sis too large, i.e. the distance (i.e. the width W) between the slit edge421 a and the second edge 151 a is more than 8 μm, the shielding regionS may influence the light emitting region. Not only the dark region butalso the bright region are shielded by the shielding region S, and inthis case, the transmittance is decreased and the contrast is no longerimproved. Hence, when the distance (i.e. the width W) between the slitedge 421 a and the second edge 151 a in the shielding region S is morethan or equal to 0 μm and less than 8 μm, the optical quality of thedisplay device can be improved.

Besides, in an embodiment of the present disclosure, the first part alsohas a designed structure. As shown in FIGS. 7A and 2B, the first part151 has a first maximum breadth W1 outside the first metal conductivelayer 12 (i.e. the region that the first metal conductive layer 12 doesnot overlap the first part 151, in other word, the region of the firstconductive layer 12 without the first region R1), the first part 151 hasa second maximum breadth W2 inside the first metal conductive layer 12,and the first maximum breadth W1 is greater than the second maximumbreadth W2. A capacitance has to be formed between the first part 151outside the first metal conductive layer 12 and the transparentconductive layer 42, so the first maximum breadth W1 has to beincreased. For the first part 151 inside the first metal conductivelayer 12, because the first part 151 has to meet the aforementionedrequirement for the charge capacity and the area of the first part 151cannot be too large to prevent the large feedthrough voltage, the secondmaximum breadth W2 (which is equal to the maximum width a shown in FIG.2) cannot be too large.

FIG. 9 is a top view of a TFT structure according to another embodimentof the present disclosure. In the display device of the presentembodiment, the features are similar to those illustrate in theaforesaid embodiment, except that the first edge 12 a of the first metalconductive layer 12 under the first part 151 is very close to thesemiconductor layer edge 14 a of the semiconductor layer 14.

In the present disclosure, the display device as illustrated in theaforementioned embodiments can be a liquid crystal display device, anorganic light emitting diode display device, a light emitting diodedisplay device or a quantum dot display device. In addition, the displaydevice as illustrated in the aforementioned embodiments can beco-operated with a touch panel to form a touch display device.Meanwhile, the display devices and the touch display devices provided bythe aforementioned embodiments can be applied to any electronic devicefor displaying images and touch sensing, for example, monitors, mobilephones, notebooks, cameras, video cameras, music players, navigationsystems, and televisions.

Although the present disclosure has been explained in relation to itsembodiment, it is to be understood that many other possiblemodifications and variations can be made without departing from thespirit and scope of the disclosure as hereinafter claimed. In addition,the designed values mentioned in the above embodiments can be used incombination without departing from the spirit and scope of thedisclosure as hereinafter claimed.

What is claimed is:
 1. A display device, comprising: a substrate; afirst metal conductive layer disposed on the substrate; a semiconductorlayer disposed on the first metal conductive layer and having a topsurface; and a second metal conductive layer disposed on the topsurface, wherein the second metal conductive layer comprises a firstpart and a second part, the first part extends toward the second part,the first part is apart from the second part in a distance and forms achannel region with the semiconductor layer, and the second metalconductive layer, the first metal conductive layer and the semiconductorlayer forms a thin film transistor structure, wherein a first extendingdirection is defined as a direction that the first part extends towardthe second part, a second direction is defined as a direction verticalto the first extending direction, a first region is defined as a regionthat the first part overlaps the first metal conductive layer, a secondregion is defined as a region that the first part overlaps thesemiconductor layer, the first part has a maximum length in the firstregion along the first extending direction, the first part has a maximumwidth in the second region along the second direction, and the maximumlength is greater than the maximum width and less than or equal to twiceof the maximum width.
 2. The display device of claim 1, wherein thefirst metal conductive layer has a first edge in the first region, thesemiconductor layer has a semiconductor layer edge in the second region;wherein the first extending direction is defined as a connection line ofa first central point of the first edge and a second central point ofthe semiconductor layer edge.
 3. The display device of claim 1, whereinthe second metal conductive layer further comprises a data line, thedisplay device further comprises a transparent conductive layer, thedata line connects to the second part, the transparent conductive layeris disposed on the second metal conductive layer, and an overlappingregion is between the second metal conductive layer and the transparentconductive layer.
 4. The display device of claim 3, wherein theoverlapping region has a width more than 0 and less than 8 μm.
 5. Thedisplay device of claim 3, wherein the transparent conductive layercomprises plural strip electrodes and plural slits alternately arranged,the slits are substantially parallel to the data line, and the secondmetal conductive layer partially overlaps with at least one of theslits.
 6. The display device of claim 5, wherein the first part of thesecond metal conductive layer partially overlaps with at least one ofthe slits.
 7. The display device of claim 5, wherein the first part ofthe second metal conductive layer has a shielding region overlapping theat least one of the slits; wherein, in the shielding region, the slithas a slit edge, the first part has a second edge, and a distancebetween the slit edge and the second edge is more than or equal to 0 μmand less than 8 μm when observing the display device at a normaldirection of the substrate.
 8. The display device of claim 1, whereinthe first part has a first maximum breadth outside the first metalconductive layer, the first part has a second maximum breadth inside thefirst metal conductive layer, and the first maximum breadth is greaterthan the second maximum breadth.
 9. The display device of claim 1,wherein the maximum width is between 1 μm to 10 μm.
 10. The displaydevice of claim 9, wherein the maximum width is between 2 μm to 6 μm.11. The display device of claim 1, wherein an area of the second regionthat the first part overlaps the semiconductor layer is between 0.78 μm²to 200 μm².
 12. The display device of claim 11, wherein the area of thesecond region that the first part overlaps the semiconductor layer isbetween 3.14 μm² to 72 μm².
 13. The display device of claim 1, wherein alength of an edge of the first part in the second region that the firstpart overlaps the semiconductor layer is between 1.57 μm to 15.70 μm.14. The display device of claim 13, wherein the length of the edge ofthe first part in the second region that the first part overlaps thesemiconductor layer is between 3.14 μm to 9.42 μm.
 15. The displaydevice of claim 1, wherein a minimum area of the second region thatfirst part overlaps the semiconductor layer satisfies the followingequation (1):A=(a/2)²×π=(π/4)×a ²≈0.785a ²  (1) wherein, “A” is an area of the secondregion that the first part overlaps the semiconductor layer; and “a” isthe maximum width of the first part in the second region that the firstpart overlaps the semiconductor layer along the second directionvertical to the first extending direction.
 16. The display device ofclaim 1, wherein a maximum area of the first region between the firstpart and the first metal conductive layer satisfies the followingequation (3):A1=(2a)×a=2×a ²  (3) wherein, “A1” is an area of the first region thatthe first part overlaps the first metal conductive layer; “a” is themaximum width of the first part in the second region that the first partoverlaps the semiconductor layer along the second direction vertical tothe first extending direction.
 17. The display device of claim 1,wherein the display device is a liquid crystal display device, anorganic light emitting diode display device, a light emitting diodedisplay device or a quantum dot display device.
 18. The display deviceof claim 1, wherein the substrate comprises glass, plastic or flexiblematerial.